Generally, electro-wetting is a technique employed in reflective type displays that changes the surface tension of an aqueous liquid by applying a voltage to it. For example, when a voltage is applied to a one pixel confined space comprising a waterproof insulator, an electrode, an aqueous liquid and a non-aqueous liquid, the surface tension of the non-aqueous liquid changes so that the non-aqueous liquid moves. When a positive voltage is applied to the liquid including the aqueous liquid and non-aqueous colored liquid and a negative voltage is applied to the insulator, the non-aqueous colored liquid moves to one side to change the reflected light, thereby adjusting the color.
An electro-wetting display device made by Dr. Robert A. Hayes at Philips Research Laboratories is described in vol. 25 of Nature at pp. 383-385, 25 Sep. 2003, includes a white substrate, a transparent electrode, a hydrophobic insulator, a colored oil, water and a metallic electrode capable of applying a voltage to the water. In the above electro-wetting display device, several components operate in a passive matrix mode. The electro-wetting display device has fast response time of no more than about 10 ms, a high reflectivity of about 40%, a contrast ratio (C/R) of about 15, low power consumption and high resolution characteristics of no more than about 160 dpi (dots per inch).